#include<iostream>
#include<cmath>
using namespace std;
double arr[1010];
int main()
{
	int n;
	int m;
	while (cin >> n >> m)
	{
		arr[0] = n;
		double sum = arr[0];
		for (int i = 1; i < m; i++)
		{
			arr[i] = sqrt(arr[i - 1]);
			sum += arr[i];
		}
		printf("%.2lf\n", sum);
	}
	return 0;
}